I always thought that using Emacs to read your mail was sort of lame. But I've been test-driving mu4e, and it's awesome. I was using Thunderbird; now I'm using Emacs with mu4e, and offlineimap (which is also awesome!) for mail synchronization. Now I have great offline mail, and a crazy-fast text-based interface. I still need to tweak spam filtering, address books, and some other adjustments to mu4e, but overall it's working for me. (A shout-out to Unalog, the discerning gentleman's microblogging platform.)
Emacs Speaks Statistics (ESS) is an add-on package for emacs text editors such as GNU Emacs and XEmacs. It is designed to support editing of scripts and interaction with various statistical analysis programs such as R, S-Plus, SAS, Stata and JAGS. Although all users of these statistical analysis programs are welcome to apply ESS, advanced users or professionals who regularly work with text-based statistical analysis scripts, with various statistical languages/programs, or with different operating systems might benefit from it the most.
I've used emacs as my primary editor, (emersive?) environment and de facto almost-OS for about ~20 years now. I read and send my email in it (vm), write/run/debug Java in it (JDEE), edit and compile my LaTeX in it, edit all other files with it, sometimes with complex macros that others would use Perl to do, and interact with shells inside of it. In the past I've edited and debugged C and C++, HTML and XML in various fooML modes. The only other major thing I have running on my workstation is my web browser (//and occasionally OpenOffice for reading Word files//). Of course, I will have additional emacs windows open on the 3 or 4 servers I am editing and running code on (and also use tramp to transparently edit remote files).